1. Field of the Invention
The present invention generally related to a method and device for independently, when such device is installed and adjusted properly, measuring and displaying the slope/grade of a road/terrain in many kinds of moving or stationary and motorized or non-motorized vehicles.
2. Description of Prior Art
Vehicle Travel Grade Indicator (VTGI) is a device designed to show the slope/grade of a road/terrain through a visible display to the driver of the vehicle who is driving on that road/terrain. It does so by complex relationships between its internal parts (i.e. shafts, gears, bush, weight, spring, and other) and substance (i.e. oil), which are later explained in detail in the “Detailed Description of the Invention” section.
So far lots of efforts have been engaged to make ways to help the transportation industries make the vehicles safer, more effective, more controllable, more comfortable, and more economical when dealing with different environmental conditions. As part of this effort, prior inventors may have tried to come up with a device that would show the slope/grade of a road on which a driver may be driving on, but to my best knowledge none have been able to come up with a device that would practically and effectively do so “independently” and on most kind of vehicles. As one can see, at present time there is no such device installed on any vehicle that generally we know of that would be in continuous use, even though the use of such device in vehicles is very crucial and vital, as described below.
Why is it crucial and vital to have a device that shows the slope/grade of the road/terrain to the driver of the vehicle on that road/terrain? Many of us have traveled or driven on interstate freeways, highways, or other roads during the winter and have been either involved ourselves or seen other vehicles slide out of roads or involved in accidents because of braking on slippery roads. Some of these events occur only because the driver was not aware of the real slope of the road on which he/she was driving. Also, imagine when bad or harsh road or environmental conditions, such as black ice, fog, heavy snow, heavy rain, heavy winds, narrow curvy roads, etc, and night driving on a hilly up and down road/terrain, make it difficult for a truck or bus driver to recognize the grade/slope of the road that he/she is driving on (due to sight/visual human error). One can therefore imagine how many trailers, trucks, buses, cars, and other type of vehicles have been involved in slippery accidents (especially during the winter months), and therefore how many precious lives and loads have been lost per year all over the world due to these type of accidents. With the knowledge of the slope/grade of the road, the driver is in better control of the safety of his/her passengers and/or loads especially during the required shifting and braking. VTGI is designed for this purpose. As one can see, a slope indicator should be an integral part of any vehicle, just like a speedometer and an odometer are.
In order to invent a device that would accurately indicate or measure the slope/grade of a course that a vehicle is traveling on, one should consider several important things:                1) The varying angle between the natural constant vertical gravity force axis and the oscillating vertical axis of the vehicle, caused by traveling up and down mountainous/hilly roads.        2) The ability to convert and show small changes in the slope/grade as a larger scale on the display of the slope/grade indicator to the operator.        3) Deviation of plummet due to change in speed (+/− accelerations) caused by pushing on the brake or gas pedals of the vehicle by the driver/operator when driving on a road/terrain (My primary hand made prototype showed that the deviation movements from the slightest push on the brake pedal by the driver created at least 6 degrees of angular deviation by the plumb from the natural constant vertical axis. When a driver presses the brake pedal hard enough, this deviation could go up to 60 degrees or more. Knowing that the grade on the U.S. freeways and most of the highways generally does not exceed 6% (which is equivalent to 3.43 degrees), one can see why overcoming this obstacle, when coming up with an invention and design for a slope/grade indicator for vehicles, is both important and hard).        
Furthermore, it is desirable if such device is:                1) Made in various price range for various users        2) Able to be made in many different reading scales        3) Flexible in installation in most vehicles        4) Able to be made both as a portable device and as a device that is installed by the manufacturer in to the vehicle        5) Easy to be calibrated by the driver        6) Independent of anything outside of its surrounded shell        7) Not requiring any source of external or internal power supply        8) Able to be made in different sizes and/or weights        9) Able to be manufactured from many different types of materials        10) Within easy reach and is easily visible to the operator of the vehicle        11) easily adjusted to the sight of the driver within seconds        12) Able to be manufactured in variety of different desired scales of reading for different fields of use        13) Able to be made to be used in most kind of motorized or non-motorized vehicles, commercial or private vehicles, regardless of the size and application of the vehicle, and on motorcycles, bicycles, and even toys        14) Accurate in showing the slope/grade and not just an estimate of such        15) Reliable        16) Able to be made so that it is not affected by external factors such as dust, bad weather, rain, snow, etc.        17) Able to measure the slope/grade quickly and continuously.        
By its intricate design, VTGI would overcome all the above obstacles. This is explained in more detail in the “Detailed Description of the Invention” section.
Here is a discussion of prior U.S. patents related to this specific method and device which make them different:                1) U.S. Pat. Nos. 3,846,781(Smith), 3,900,073(Crum), and 5,450,909 (Stevenson) are only for earthmoving/earth working equipment.        2) U.S. Pat. No. 4,583,296 (Dell'Acqua) relies on electrically-conductive liquid/material and electrodes and measurement of electrical resistance.        3) U.S. Pat. No. 5,132,906 (Sol, et al.) “estimates” the hill slope and relies on vehicle and engine measurements.        4) U.S. Pat. No. 5,187,977 (Koschorek, et al.) is for recognition of a rising slope and not the measurement of such slope. Also, it relies on at least one sensor in relationship to the axle load of the rear axle or the front axle of the vehicle with electronic component.        5) U.S. Pat. No. 5,351,540 (Gee) relies on two different sensors for generating two different signals and a grade angle generator to come up with the grade angle.        6) U.S. Pat. No. 5,446,658 (Pastor, et al.) “estimates” incline angle of a road for a “front wheel drive” vehicle and relies on a rotational speed sensor on each non-driven rear wheel, and on longitudinal and lateral accelerometers mounted to the vehicle chassis above the centerline of the rear axle.        7) U.S. Pat. No. 5,596,826 (Barden) is a level indicating mechanism for a “work machine”.        8) U.S. Pat. No. 7,400,946 (Lee, et al.) is a method and apparatus for measuring the velocity of a vehicle.        9) U.S. Pat. No. 5,797,109 (Aminpour, et al.) is a method and relies on information related to driven axles (rolling free of slip) and the non-driven axles of the vehicle.        
Methods and devices of prior art therefore have shown to have one of the following drawbacks: the limit of their accuracy, dependency (i.e. on sensors, axles or other moving part of the vehicle, and/or electronic power), limited application (i.e. earthmoving equipment), or specific type of vehicles (i.e. front wheel drive).